Starch hydrolyzates are conventionally prepared by hydrolyzing starch substrates with amylase. Initially, the food industry's primary interest resided in high F.E. conversion syrups which could serve as a low cost sweetener. Within the last decade or so, low D.E. starch hydrolyzates have become increasingly attractive for certain food applications, especially when non-sweet, non-hygroscopic, bland, bodying or bulking characteristics are desired.
The proportion of fermentable extracts (i.e., F.E.) and high molecular weight saccharides in a given starch hydrolyzate will primarily depend upon the particular type of amylase employed in its preparation and the extent of starch hydrolysis. In producing starch hydrolyzates, the D.E. values are frequently used to characterize the composition and functional properties of the hydrolyzate. Since the enzymatic hydrolysis of starches generally follows substantially the same pattern or mode of hydrolysis, a hydrolyzate manufacturer cannot substantially alter or control the saccharide distribution in low D.E. starch hydrolyzates simply by altering its D.E. value.
If the starch hydrolyzate manufacturer were able to substantially alter and control the saccharide distribution, starch hydrolyzates could be more suitably made and adapted for specific end-uses. This would significantly improve upon the functionality and adaptability of low D.E. starch hydrolyzates in a broader spectrum of food products.
Heretofore the art has been relatively unsuccessful in its attempts to control or alter the saccharide distribution of starch hydrolyzates. Alpha-amylases are conventionally used to produce low D.E. starch hydrolyzates such as maltodextrins. In preparing low D.E. starch hydrolyzates from underivatized starches, the art has been confronted with the dilemma of either providing an excessive amount of fermentable sugars or an excessive amount of high molecular polysaccharides, or both, with little, if any, control over the production of saccharides having a D.P. of 30 or higher. If the alpha-amylase hydrolysis reaction is allowed to proceed towards completion, the resultant starch hydrolyzate will have a high D.E. and a high proportion of fermentable sugars and a low amount of D.P..sub.30+ saccharide. Conversely, if the starch hydrolysis is continued for a relatively short period of time, the resultant hydrolyzate will be characterized as containing a negligible amount of fermentable sugars and a large proportion of insufficiently hydrolyzed polysaccharides. These insufficiently hydrolyzed saccharides are generally undesirable because of their difficulty to disperse in aqueous systems and susceptibility to retrogradation. Control of the saccharide distribution, especially above D.P..sub.10+ would enable the art to tailor-make and adapt starch hydrolyzates to a broader spectrum of food products.
Starch derivatives are recognized as yielding different hydrolyzate products from those which are obtained from underivatized starches. In British Patent Specification No. 1,171,893, cold-water-soluble, low-viscosity, gum-like starch products are prepared by hydrolyzing derivatized amylopectin starches with amylases. Similarly, U.S. Pat. No. 3,505,110 discloses a process for preparing sugar ethers by saccharifying liquefied hydroxypropylated starches with starch saccharifying enzymes. The sugar ethers of U.S. Pat. No. 3,505,110 are reportedly non-caloric and essentially non-degradable by salivary amylases. Derivatized starch hydrolyzates characterized as possessing improved freeze-thaw stability properties are disclosed in U.S. Pat. No. 3,525,672. These derivatized starch hydrolyzates are reportedly prepared by hydrolyzing inhibited amylopectin starch granules with exo-amylases. Another process for preparing derivatized starch conversion products from cross-linked and inhibited starch granules has been disclosed in U.S. Pat. No. 3,804,716.
In the paper and textile industry, the hydrolysis of starch derivatives with alpha-amylase has been reported. For purposes of improving the paper coating character of starch hydrolyzates, granular cyanoethyl starches of a low degree of substitution (d.s.) are hydrolyzed with alpha-amylase in U.S. Pat. No. 3,689,361. To improve upon the liquefaction efficacy of alpha-amylase during paper sizing and warp sizing operations, acetylated granular starches (prepared in the presence of ferrous salts and hydrogen peroxide) have been disclosed in U.S. Pat. No. 3,557,091.